1. Field of the Invention
The present invention relates to an uneven substrate for manufacturing a magnetic recording medium capable of performing high-density recording, a method of manufacturing such an uneven substrate, a magnetic recording medium and a method of manufacturing a magnetic recording medium, and a magnetic recording apparatus including such a magnetic recording medium.
2. Background Art
A hard disk drive is a recording apparatus including a housing and a magnetic disk provided within the housing. The magnetic disk is formed by depositing a film of a magnetic material (magnetic film) on a glass substrate. A magnetic film is composed of fine particles each having magnetic domains. Between records, noise is generated in accordance with the particle size. In order to achieve high density recording, the size of magnetic domains of a magnetic recording medium, which is the information recording unit, should be made smaller.
However, if the size of magnetic domains is made too small, a thermal fluctuation problem occurs, which makes it difficult to maintain records at a room temperature. Accordingly, at present, two kinds of magnetic recording media are proposed, in which a recording layer composed of a generally-used continuous magnetic material is cut at portions unable to perform magnetic recording, thereby improving a recording efficiency while maintaining the size of magnetic domains.
In one of the aforementioned two kinds of magnetic recording media, a discrete magnetic recording medium, adjacent recording tracks in a magnetic disk are separated by a non-recording section, thereby decreasing the track pitch while maintaining the track position data (for example, Japanese Patent Laid-Open Publication No. 2003-16621). It is possible to prevent the interference between recording tracks by physically separating the magnetism of recording tracks of a magnetic material and eliminating the effect of the leakage magnetic field of a recording and reproducing head, thereby narrowing the tracks.
In the other kind of magnetic recording medium, a patterned medium, the magnetic particles are regularly arranged in a nonmagnetic base material, and the size of each magnetic particle is regarded as the size of the recording magnetic domain (for example, Japanese Patent Laid-Open Publication No. 2000-251236). In this manner, it is possible to fix the recording positions and to solve the thermal fluctuation problem at the same time. However, highly accurate processing steps are required to regularly arrange magnetic particles having a continuous magnetic property and to process a magnetic material. In particular, the degradation in the size and the direction of the vertical magnetic anisotropy of a recording film is a significant problem. Furthermore, although the head flying height of a recording and reproducing head should be lowered in order to improve the recording efficiency, it is difficult to decrease the flying height, and a number of smoothing steps are required when a patterned medium, which has a number of projections and depressions, is used.
When a discrete magnetic recording medium is used, recording is performed within a recording track having a predetermined width. However, the recording position tends to shift because of a shift in the track direction of the recording and reproducing head within a track. Thus, there is a problem in that the S/N ratio of the recording and reproducing is degraded.
When a patterned medium is used, a good S/N ratio can be obtained since the recording sections are completely separated to always fix the recording positions. However, because the recording sections are separated, there is a problem in that the area that can be used for recording is small, and the intensity of a reproduction signal is low.